Revolutionary network of computers downs commercial server (5)
I believe the answer is:
nadal
'server' is the definition.
(tennis player Rafael Nadal, someone who serves)
'revolutionary network of computers downs commercial' is the wordplay.
'revolutionary' is a reversal indicator.
'network of computers' becomes 'LAN' (Local Area Network).
'downs' is an insertion indicator (down can mean to swallow).
'commercial' becomes 'ad' (abbreviation for advertisement).
'lan' enclosing 'ad' is 'ladan'.
'ladan' backwards is 'NADAL'.
(Other definitions for nadal that I've seen before include "Top tennis player" , "Rafael __, Spanish tennis player" , "Star with a 30 [RACKET]" , "tennis champion" , "court figure" .)